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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

i86

NICKEL STEELS

NICKEL   STEELS

Nickel steels are valued particularly on account of their strength and

elasticity.

Their analysis includes determinations of the usual elements of ordinary
steels and also of the nickel and, sometimes, chromium and tungsten.

1. Determination of the Nickel by means of Dimethylglyoxime.—

In a solution which is either ammoniacal or faintly acid with acetic acid,
dimethylglyoxime precipitates nickel quantitatively as nickeloxime ; this
is a red, crystalline precipitate which can readily be collected on a Gooch
crucible, washed and weighed.

Procedure. With steels containing less than 3% Ni, 2 grams, or pro-
portionately less with richer steels,1 are treated in a porcelain dish, covered
with a clock-glass, with nitric acid (D 1-2). The solution is evaporated
to dryness and the residue calcined and taken up in hydrochloric acid as
indicated for the determination of silicon in steels and cast-iron (see p. 172).
To the hydrochloric acid solution, freed from silica and diluted to 250-
300 c.c., are added about 7 grams of tartaric acid dissolved in a little water
for each gram of metal taken, the liquid being then rendered alkaline with
dilute ammonia so as to give a perfectly clear solution.

The latter is then again slightly acidified with hydrochloric acid, heated
almost to boiling and 10-20 c.c. of a i% solution of dimethylglyoxime in
alcohol (0-05 gram of nickel requires about 20 c.c.) added drop by drop
and with shaking ; ammonia is then added until the liquid just smells dis-
tinctly. The nickel is separated as a voluminous, crystalline precipitate.
After a few minutes, 5-10 c.c. of the dimethylglyoxime are added to ascertain
if the precipitation is complete, and when this is so the liquid is heated for
about 30 minutes on a water-bath and, when cold, filtered through a Gooch
crucible. The precipitate is washed repeatedly with hot water, dried at 120°
and weighed ; the weight obtained, multiplied by 0-2032 gives the amount
of nickel in the sample taken.2

2.  Determination of the Carbon, Phosphorus,  and  Sulphur.—

See Iron, i, 4, 5.

3.  Determination of the Silicon.—The silica separating when the
metal is treated with nitric acid, is weighed (see above and Iron, 2).

4.  Determination of the Manganese.—In presence of small quan-
tities of nickel, the manganese may be determined by Volhard's volumetric
method (see p. 197).

If, however, nickel is present in large quantities, the sample is dissolved
in hydrochloric acid and the iron eliminated by treatment with ether in
Rothe's apparatus, the nickel being then separated from the manganese by
means of ammonia and bromine water.

1  For steels with 10-25% of nickel, it is advisable to use i gram and, after elimina-
tion and, if required, estimation of the silica, to make up to a definite volume and take
an aliquot part containing about 0-05 gram of nickel for the determination.

2  For the volumetric determination of nickel in steels, see Belasio and Marchion-
neschi, Awnali di Chim. Applicata   1914, I, p. 133.open platinum crucible, are then